Manual machine tool

ABSTRACT

The invention is based on a hand power tool, in particular a hammer drill, with a drivable drive mechanism ( 12 ) accommodated in a housing ( 10 ) and a mechanical hammer unit ( 14 ), which is for percussion-driving a tool ( 16 ) in a tool holding fixture ( 18 ) and has a hammer ( 20 ) that can be driven in its hammering motion by means of a driver unit ( 22 ), which has at least one annular curved path ( 24, 26 ) with raised areas and recessed areas oriented axially toward the tool and has a feeler unit ( 28 ), which is operationally connected to the hammer ( 20 ) and which, by means of at least one feeler element ( 30 ), can be brought into operational connection with the raised areas and recessed areas of the curved path ( 24, 26 ).  
     The invention proposes that the feeler unit ( 28 ) has at least two feeler elements ( 30 ) that can be brought into operational connection with the curved path ( 24, 26 ).

PRIOR ART

[0001] The invention is based on hand power tool according to thepreamble to claim 1.

[0002] DE 197 26 383 A1 has disclosed a hand power tool that defines thespecies, specifically an electrically driven hammer drill. The hammerdrill has a rotary driven working spindle that is supported in a housingand in turn drives a tool holding fixture of a tool. The hammer drillalso has a mechanical hammer unit with a hammer, which can move axiallyinside the working spindle embodied as a hollow shaft and can beaccelerated in the axial direction, and which acts directly orindirectly on a shaft of the tool during operation. The hammer is actedon by a driver unit, which converts a rotary motion of the workingspindle into an axial acceleration of the hammer.

[0003] The driver unit has a feeler unit that can move axially androtates synchronously with the working spindle and that is guided withaxial play between two annular curved paths, which do not rotate inrelation to the working spindle and have raised areas and recessed areasoriented toward each other in the axial direction of the workingspindle. The feeler unit is constituted by an annular component, whichcan be moved on the hammer in the axial direction, counter to acompression spring and which has a feeler element extending radiallyoutward, which reaches through a slot in the working spindle between thecurved paths and can thus bring the feeler unit into an operativeconnection with the curved paths.

[0004] For a switching on and off of the hammer unit, the curved pathoriented toward the tool is supported so that it can move axially intandem with the working spindle. If the tool is pressed against aworking surface, the working spindle at the curved path oriented towardthe tool is slid axially toward the curved path oriented away from thetool, counter to an idling spring embodied as a compression spring sothat the feeler element comes into contact with the two curved pathsduring a rotating motion. The hammer unit is switched on.

[0005] If the tool is lifted up from the working surface, the curvedpath oriented toward tool and the working spindle are restored to theirinitial position by the idling spring. The distance between the twocurved paths is thereby enlarged to such an extent that the feelerelement in rotate freely between the two curved paths, without cominginto contact with them. The hammer unit is switched off.

ADVANTAGES OF THE INVENTION

[0006] The invention is based on a hand power tool, in particular ahammer drill, with a drivable drive mechanism accommodated in a housingand a mechanical hammer unit, which is for percussion-driving a tool ina tool holding fixture and has a hammer that can be driven in itshammering motion by means of a driver unit, which has at least onecurved path with raised areas and recessed areas oriented axially towardthe tool and has a feeler unit, which is operationally connected to thehammer and which, by means of at least one feeler element, can bebrought into operational connection with the raised areas and recessedareas of the curved path.

[0007] The invention proposes that the feeler unit has at least two andpreferably three or more feeler elements that can be brought intooperational connection with the curved path. A tilting moment on thefeeler unit and the hammer can be prevented and a centering of thefeeler unit on the curved path can be achieved. The efficiency can beincreased and the wear can the reduced.

[0008] If the feeler elements have at least one sloped surface at leastpartly oriented in the rotation direction and/or counter to the rotationdirection, the feeler elements can be advantageously guided with aminimum of wear from a recessed area of a curved path onto a raised areaof the curved bath and from a raised area of the curved path into arecessed area of the curved path. A tilting contact between the feelerelements and the curved paths can be prevented. The sloped surfaces can,for example, be constituted by a concavely curving sloped surface or bya phase.

[0009] In order to assure a reliable engagement and disengagement of thehammer unit and to assure a reliable neutral position, when in thisneutral position, a respective stop limits the movement of the feelerelements of the feeler unit in the axial direction toward at least onecurved path, or when there are two curved paths, advantageously limitsthis movement of the feeler elements in the axial direction toward bothfunctional curved paths. If the drive mechanism is supported in anaxially mobile fashion, and if a stop is constituted by a device affixedto the drive mechanism, for example a securing ring, a shoulder formedonto the drive mechanism, or the like, then a disengaging movement ofthe drive mechanism can be advantageously used to correspondinglyposition a stop in order to limit the movement of the feeler elements ofthe feeler unit.

[0010] Another embodiment of the invention proposes that a stop isconstituted by a component, which, when the hammer unit is in ahammering position, forms a part of curved path, which permits anembodiment that is particularly compact and lightweight to be produced.This can be achieved in a structurally simple manner particularly inthat the component is comprised of a ring with openings, which extend inthe circumference direction and are separated by struts, and in thehammering position, partial regions of the curved paths protrude throughthe openings, the struts plunge into recesses between the partialregions, and form a part of the curved path.

[0011] Instead of two curved paths between which the feeler unit isdisposed, the driver unit can also be embodied with only one curvedpath, one whose raised areas and recessed areas are oriented axiallytoward the tool. The device must be balanced in such a way that thefeeler unit is moved back toward the curved path by a spring and/or bythe hammer rebounding off a stop surface. This permits additionalcomponents, space, and weight to be saved in comparison to a driver unitwith two curved paths.

DRAWINGS

[0012] Further advantages ensue from the following description of thedrawings. The drawings show an exemplary embodiment of the invention.The drawings, the specification, and the claims contain numerousfeatures in combination. One skilled in the art will also suitablyconsider the features individually and unite them in other meaningfulcombinations.

[0013]FIG. 1 shows a side view of a hammer drill,

[0014]FIG. 2 shows a sectional view of an enlarged detail II from FIG.1,

[0015]FIG. 3 shows a detail of a hammer unit from FIG. 2 duringhammering operation,

[0016]FIG. 4 shows a section along the line IV-IV in FIG. 3,

[0017]FIG. 5 shows a section along the line V-V in FIG. 4, and

[0018]FIG. 6 shows a curved path with an annular component thatconstitutes a stop.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

[0019]FIG. 1 shows a hammer drill in a side view, with a drive mechanism12 (FIGS. 2 and 3) embodied as a spindle, which can be driven to rotatein a housing 10 by an electric motor that is not shown in detail. Thehammer drill has a mechanical hammer unit 14 for percussion-driving adrill bit 16, which is held in a tool holding fixture 18. The hammerunit 14 has a hammer 20, which can be driven in its hammering motion bya driver unit 22 and is movably supported in the drive mechanism 12,which is embodied as a hollow shaft. On an end oriented toward the toolholding fixture 18, the drive mechanism 12 is supported by a needlebearing 104 that encompasses the drive mechanism. At an end orientedaway from the tool holding fixture 18, the drive mechanism 12 issupported by a ball bearing 108, which is disposed on a plastic bearingjournal 106 that is formed onto the housing 10 and extends radiallyinside the drive mechanism 12, which permits space to be saved.Alternative slide bearings 104 a and 108 a are shown in the lower half;the slide bearing 108 a remote from the tool holding fixture 18 isdisposed on a separate metal bearing journal 106 a that is press-fittedinto the housing 10.

[0020] The driver unit 22 has two annular curved paths 24, 26non-rotatably situated in the housing 10, which each have fivesinusoidal recessed areas and raised areas oriented toward each other inthe axial direction of the drive mechanism 12. In principle, however, itis also conceivable for there to be a larger or smaller number of raisedareas and recessed areas. Furthermore, curved paths can be used, whichhave different amplitudes and/or curve progressions, for example curvesthat also deviate from a sinusoidal form. In a hand power tool with atool that is stationary in the rotation direction, curved paths withonly one raised area and one recessed area would actually also beconceivable.

[0021] Between the curved paths 24, 26, there is a feeler unit 28, whichcan be driven to rotate. The feeler unit 28 is comprised of an annularcomponent that has five strut-shaped feeler elements 30 extendingradially outward and distributed evenly over the circumference and hastwo strut-shaped driver elements 52 extending radially inward (FIG. 4).

[0022] The component comprising the feeler unit 28, with its driverelements 52 extending radially inward, reaches between two sliding rings64 disposed on the hammer 20. The feeler unit 28 is supported so that itcan rotate between the sliding rings 64 and so that it can be movedaxially on the hammer 20 by the sliding rings 64, between two helicalcompression springs 54, 56 (FIGS. 2 and 3). In principle, a feeler unitand a hammer could also be non-rotatably connected to each other. Thehelical compression spring 54 closer to the tool holding fixture 18 issupported, in the direction oriented toward the tool holding fixture 18,against a stop 58 formed onto the hammer 20 and acts on the feeler unit28 in the direction oriented away from the tool holding fixture 18 bymeans of a sliding ring 64. The helical compression spring 56 remotefrom the tool holding fixture 18 is supported, in the direction orientedaway from the tool holding fixture 18, against the hammer 20 by means ofa spring support 60 and by means of a securing ring 62 fastened to thehammer 20 and acts on the feeler unit 28 in the direction orientedtoward the tool holding fixture 18 by means of a sliding ring 64. Thehelical compression springs 54, 56 are prestressed toward each other.

[0023] In addition, the feeler unit 28, with its feeler elements 30extending radially outward, reaches through slot-shaped openings 66extending axially in the drive mechanism 12 and is form-fittinglyconnected in the rotation direction 32 to the drive mechanism 12. Bymeans of the feeler elements 30, the feeler unit 28 remainsoperationally connected to the curved paths 24, 26 during a hammeringoperation. In lieu of a feeler unit that can be driven to rotate, inprinciple, the curved paths could also be designed so that they could bedriven to rotate.

[0024] In order to keep the wear between the feeler elements 30 and thecurved paths 24, 26 as low as possible, the feeler elements 30 havesloped surfaces 34, 36, which are comprised of phases, oriented towardthe two curved paths 24, 26, in the rotation direction 32 and counter tothe rotation direction 32.

[0025] The drive mechanism 12 is supported so that can be moved in theaxial direction along with the tool holding fixture 18. If the hammerdrill is pressed with the drill bit 16 against a working surface, thedrill bit 16, together with the tool holding fixture 18 and the drivemechanism 12, is slid into the housing 10, as shown in the upper half ofFIG. 2 down to the center line of the drive mechanism 12. By means of asecuring ring 68 and an axial bearing 70, the drive mechanism 12 acts inthe axial direction on a cup-shaped sleeve (FIG. 3). The sleeve is fixedin the rotation direction in the housing 10 by means of cylindrical pins82 and is supported so that it can slide in the axial direction (FIGS. 2and 3).

[0026] The cup-shaped sleeve extends axially with its cup wall in thedirection oriented away from the tool holding fixture 18, and a part ofthe front curved path 24 is formed onto an end of the cup wall orientedtoward the feeler unit 28. A helical compression spring 72, which isdisposed in the sleeve, radially encompasses the drive mechanism 12, andis supported, in the direction oriented away from the tool holdingfixture 18, against an annular spring plate 44 affixed to the housing,acts on the bottom of the sleeve in the direction toward the toolholding fixture 18. By means of the drive mechanism 12, the sleeve andalong with it, a part of the front curved path 24, is slid counter tothe helical compression spring 72 until the sleeve strikes against thespring plate 44.

[0027] If the sleeve is slid into its end position oriented away fromthe tool holding fixture 18, partial regions 50 of the curved path 24formed onto the end of the sleeve reach through circumferentiallyextending openings 48 of the spring plate 44 (FIG. 6). The openings 48are separated by struts 46, and in the end position or hammeringposition, plunge into recesses 74 in the cup wall of the cup-shapedsleeve, between the partial regions 50, and form a part of the curvedpath 24.

[0028] In the hammering position, the rotary driven feeler unit 28 comesinto contact with the curved paths 24, 26 by means of its feelerelements 30 and drives the hammer 20 in a translatory fashion by meansof the helical compression springs 54, 56. The hammer 20 acts in atranslatory fashion on a snap 76, which strikes against an end of thedrill bit 16 oriented toward the housing 10. The hammer unit 14 isswitched on. Depending on the design, the feeler unit 28 leaves thecurved path 26, which is oriented away from the tool holding fixture 18,before or after a dead center of the tool. It is also possible for thereto be a design in which the feeler unit 28 continuously travels on thecurved path 26 in a steady state. In lieu of a stop on the drill bit 16,it would also be conceivable for a hammer or a snap to strike directlyor indirectly against a drive mechanism, a tool holding fixture, oranother component viewed as suitable by one skilled in the art.

[0029] If the drill bit 16 is lifted up from the working surface, thenby means of the sleeve bottom, the helical compression spring 72 slidesthe cup-shaped sleeve with the partial regions 50 of the curved path 24,the drive mechanism 12, and the tool holding fixture 18 with the drillbit 16 into their initial position, until the cup-shaped sleeve, with aradially outward extending collar 78 formed onto it, comes into contactwith a stop 80 in the housing 10.

[0030] The partial regions 50 of the curved path 24 thereby traveltoward the tool holding fixture 18 through the openings 48 of the springplate 44, whose axial end oriented toward the feeler unit 28 constitutesa stop 38, which, in the neutral position of the hammer unit 14, limitsthe axial movement of the feeler unit 28 and its feeler elements 30 inthe direction of the curved path 24 or the functional curved path 24.

[0031] Along with the drive mechanism 12, a device 42, which is fastenedto the drive mechanism 12 and is comprised of a securing ring, movesaxially through the annular curved path 26, which is oriented away fromthe tool holding fixture 18 and is affixed in the housing 10 axially andradially, and constitutes a second stop 40, which limits the movement ofthe feeler unit 28 and its feeler elements 30 axially in the directionof the curved path 26 (FIG. 2). The stops 38, 40 reliably prevent acontact between the feeler elements 30 and the functional curved paths24, 26 in the neutral position of the hammer unit 14.

[0032] In the direction of the tool holding fixture 18, the securingring also supports a spring plate 84 for a locking spring 86, which actson a locking disk 88 in the direction oriented away from the toolholding fixture 18 (FIG. 2). With driver elements 90 oriented radiallyinward, the locking disk 88 engages in a form-fitting manner in therotation direction in recesses of the drive mechanism 12 and on the sideoriented away from the tool holding fixture 18, has axially extendinglocking pins 92. The locking pins 92 engage in a form-fitting manner inthe rotation direction in recesses of a gear 94 that is supported inrotary fashion on the drive mechanism 12 and meshes with a pinion 102formed onto a driveshaft 100. In the direction oriented away from thetool holding fixture 18, the gear 94 is supported on the drive mechanism12 by a stop ring 96 and a securing ring 98.

[0033] If an existing torque exceeds a particular value, the lockingring 18 can move out of the way in the axial direction toward the toolholding fixture 18, counter to the locking spring 86, the locking pins92 can slide in the rotation direction over the recesses in the gear 94,and a rotary drive of the drive mechanism 12 can be interrupted.Reference Numerals 10 housing 66 opening 12 drive mechanism 68 securingring 14 hammer unit 70 axial bearing 16 tool 72 helical compressionspring 18 tool holding fixture 74 recess 20 hammer 76 snap 22 driverunit 78 collar 24 curved path 80 stop 26 curved path 82 cylindrical pin28 feeler unit 84 spring plate 30 feeler element 86 locking spring 32rotation direction 88 locking disk 34 sloped surface 90 driver element36 sloped surface 92 locking pin 38 stop 94 gear 40 stop 96 stop ring 42device 98 securing ring 44 component 100 driveshaft 46 strut 102 pinion48 opening 104 needle bearing 50 partial regions 106 bearing journal 52driver element 108 ball bearing 54 helical compression spring 56 helicalcompression spring 58 shoulder 60 spring support 62 securing ring 64sliding ring

1. A hand power tool, in particular a hammer drill, with a drivable drive mechanism (12) accommodated in a housing (10) and a mechanical hammer unit (14), which is for percussion-driving a tool (16) in a tool holding fixture (18) and has a hammer (20) that can be driven in its hammering motion by means of a driver unit (22), which has at least one curved path (24, 26) with raised areas and recessed areas oriented axially toward the tool and has a feeler unit (28), which is operationally connected to the hammer (20) and which, by means of at least one feeler element (30), can be brought into operational connection with the raised areas and recessed areas of the curved path (24, 26), characterized in that the feeler unit (28) has at least two feeler elements (30) that can be brought into operational connection with the curved path (24, 26).
 2. The hand power tool according to claim 1, characterized in that the feeler elements (30) have at least one sloped surface (34) at least partly oriented in the rotation direction (32).
 3. The hand power tool according to claim 1 or 2, characterized in that the feeler elements (30) have at least one sloped surface (34) at least partly oriented counter to the rotation direction (32).
 4. The hand power tool according to one of the preceding claims, characterized in that in a neutral position, a stop (8, 40) limits the movement of the feeler elements (30) of the feeler unit (28) in the axial direction toward at least one functional curved path (24, 26).
 5. The hand power tool according to claim 4, characterized in that the drive mechanism (12) is supported so that it can move axially and a stop (40) is constituted by a device (42) affixed to the drive mechanism (12).
 6. The hand power tool according to claim 5, characterized in that the device (42) is constituted by a securing ring fastened to the drive mechanism (12).
 7. The hand power tool according to one of claims 4 to 6, characterized in that a stop (38) is constituted by a component (44), which forms a part of a curved path (24) in a hammering position of the hammer unit (14).
 8. The hand power tool according to claim 7, characterized in that the component (44) is constituted by a ring with openings (48), which extend in the circumference direction and are separated by struts (46), and in the hammering position, partial regions (50) of the curved path (24) protrude through the openings (48), the struts (46) plunge into recesses (74) between the partial regions (50), and form a part of the curved path (24).
 9. The hand power tool according to one of the preceding claims, characterized in that the driver unit has only one curved path. 